The strike, the first to hit Africa's biggest mobile phone operator since its formation in 1994, is forcing the company to turn away customers hoping to buy mobile phones at some of its stores due to supply shortages.

A strike over higher pay at South African mobile phone operator MTNGroup stretched into its fourth week on Monday, disrupting the supply of some new mobile phones.

The strike, the first to hit Africa's biggest mobile phone operator since its formation in 1994, is forcing the company to turn away customers hoping to buy mobile phones at some of its stores due to supply shortages.

"We are due to meet MTN later this week but in the meantime the strike continues," said Tshepo Matlau, a national organiser at Communications Workers' Union (CWU).

Themba Nyathi, MTN's human resources head and the spokesman on the industrial action, was not available to comment.